Preparation and quantum size effect of CuBr microcrystal doped glasses by the sol-gel process

Abstract

CuBr microcrystal doped glasses were prepared by the sol-gel process. Gels synthesized through hydrolysis of a complex solution of Si(OC 2H 5) 4, Al(OC 4H 9) 3 and CuBr were heated to 900°C in a nitrogen atmosphere to form cubic CuBr microcrystals with diameters ranging from 5 to 8 nm. In the optical absorption spectra of samples heated above 700°C, peaks were observed at ca. 3.05 and 3.20 eV at 77 K. These peaks are attributed to the Z 1,2 and Z 3 excitons, respectively, in CuBr microcrystals and are shifted to the higher energy side as the sizes of the CuBr crystals decrease. This phenomenon is interpreted in terms of a quantum confinement effect of the excitons in the CuBr microcrystals.